1. Way back in October Do you remember?
7x10
32 x 100
23 x 1000
430 ÷10
1200 ÷ 100
3234 ÷ 1000
Multiplying whole numbers by 10,100,1000
Dividing whole numbers by 10,100,1000
234

2. TODAY We Are Learning To: Multiply and Divide decimals by 10,100,1000
(in the same way as we did whole numbers)
We say that we move the decimal point, but in reality we are moving the numbers!

3. x10
Ten
thousand
10.000’s
thousands
1,000’s
Hundreds
100’s
Tens
10’s
Units
1’s
d.p.
Tenths
1/10’s
Hundredths
1/100’s
Left
x10 2 5
x10 2 5
0.25 x 10 = 2.5
When we multiply by 10 all the numbers drive one column to the left. They each get bigger by a factor of 10.
25 X 10 = 250

4. x100
Ten
thousand
10.000’s
thousands
1,000’s
Hundreds
100’s
Tens
10’s
Units
1’s
d.p.
Tenths
1/10’s
Hundredths
1/100’s
Left 2 5
x100
x100 2 5
0.25 x 100 = 25
When we multiply by 100 all the numbers drive TWO columns to the left. They each get bigger by a factor of 100.
25 X 10 = 250

5. x1000
Ten
thousand
10.000’s
thousands
1,000’s
Hundreds
100’s
Tens
10’s
Units
1’s
d.p.
Tenths
1/10’s
Hundredths
1/100’s
Left 2 5
x1000
x1000 2 5
0.25 x 1000 = 250
When we multiply by 1000 all the numbers drive THREE columns to the left. They each get bigger by a factor of 1000.
25 X 10 = 250

6. Thousand
1000
Hundred
100
Ten 10
Units
1’s
d.p.
Tenths
1/10’s
Hundredths
1/100
1/1000
1/10000
1/100000
right
÷10
Divide
By 10 6 1 3
Divide
By 10 6 1 3
310.6 ÷ 10 = 31.06
When we divide by 10 all the numbers drive one column to the right. They each get smaller by a factor of 10.

7. Thousand
1000
Hundred
100
Ten 10
Units
1’s
d.p.
Tenths
1/10’s
Hundredths
1/100
1/1000
1/10000
1/100000
right
÷100
Divide
By 100 6 1 3
Divide
By 100 6 1 3
310.6 ÷ 100 = 3.106
When we divide by 100 all the numbers drive TWO columns to the right. They each get smaller by a factor of 100.

8. Thousand
1000
Hundred
100
Ten 10
Units
1’s
d.p.
Tenths
1/10’s
Hundredths
1/100
1/1000
1/10000
1/100000
right
÷1000 6 1 3
Divide
By 1000
Divide
By 1000 6 1 3
310.6 ÷ 1000 =
When we divide by 1000 all the numbers drive THREE columns to the right. They each get smaller by a factor of 1000.

9. Time for some BINGO practise!
Moving the point works but understanding what actually happens is important 

10. Draw a 3 x 3 grid as shown below:
TASK (BINGO)
Draw a 3 x 3 grid as shown below:
Place any nine numbers below into the grid (repeats forbidden) 10

11. TASK (BINGO)
What is 5.2 x 10? 52 11

12. TASK (BINGO)
What is 47.3 ÷ 10?
4.73 12

13. TASK (BINGO)
What is 47.3 x 100?
4730 13

14. TASK (BINGO)
What is 5.2 ÷ 10?
0.52 14

15. TASK (BINGO)
What is 3.56 x 1000?
3560 15

16. TASK (BINGO)
What is 3.56 ÷ 10?
0.356 16

17. TASK (BINGO)
What is 47.3 ÷ 100?
0.473 17

18. TASK (BINGO)
What is 5.2 x 1000?
5200 18

19. TASK (BINGO)
What is 3.56 ÷ 100?
0.0356 19

20. TASK (BINGO)
What is 47.3 ÷ 1000?
0.0473 20

21. TASK (BINGO)
What is 5.2 x 100?
520 21

22. TASK (BINGO)
What is x 100?
35.6 22

23. TASK (BINGO)
What is x 100?
47.3 23

24. TASK (BINGO)
What is x 1000?
3.56 24

25. TASK (BINGO)
What is 520 ÷ 100?
5.2 25

26. TASK (BINGO)
What is x 10000?
473 26